▎ 摘　　要

The morphology of graphene synthesized via atmospheric pressure chemical vapor deposition (APCVD) process was investigated with respect to the hydrogen introduction in each process step. A pristine monolayer graphene was obtained in the condition where hydrogen was excluded in all the steps. The study of growth mechanism of this hydrogen-excluded APCVD process suggests that hydrogen plays a critical role in determining the rate-limiting step, which further determines whether or not a monolayer graphene can be achieved, irrespective to the roughness of the surface. Particularly, the dominant kinetic regime changed, depending on the introduction of hydrogen in the growth step. Finally, electric properties of the graphene via the hydrogen-excluded APCVD process were characterized and compared with the one via the low pressure CVD process, along with the characterization of etch pits in a graphene-passivated etch test. The resulted better performance of the former graphene in both cases suggests that this method can be considered as an alternative but easier route for the synthesis of monolayer graphene. (C) 2013 Elsevier Ltd. All rights reserved.